US study shows no association of wireless phones with brain cancer
In "What's New" of November 1999, we reported results of a study by Muscat that were presented at a conference in June1999. This study has now been published in the Journal of the American Medical Association. A total of 469 persons with brain cancer at 5 US academic medical centres were compared with 422 control subjects without brain cancer, with regards to their use of handheld cellular telephones. The authors found that the use of handheld cellular telephones was unrelated to the risk of brain cancer.
Reference: Muscat JE, Malkin MG, Thompson S, Shore RE, et al. Handheld cellular telephone use and risk of brain cancer. JAMA 2000;284:3001-3007.
Because of recent public interest, the New England Journal of Medicine has released an article on cellular telephone use and brain tumours before its publication date. The final version will be published on January 11, 2001.This study from the National Cancer Institute in the USA was conducted between 1994 and 1998, and compared 782 persons with brain tumour to 799 control subjects. Again there was no evidence that the risk of brain tumour was increased among those that used cell phones. Further, the authors did not find higher risks among those that used their phones for 60 or more minutes per day or regularly for 5 or more years.
Reference: Inskip PD, et al. http://www.nejm.org/content/inskip/1.asp
Pregnant rats were exposed throughout pregnancy to a low level (0.1mW/cm²). 900 MHz pulsed EMF that approximated the highest legal exposure of normal populations to the radiation of base antennas of the GSM digital phone technology. Control rats were sham-exposed. The average whole body SAR was between 17.5 and 75 mW/kg. There were no differences in litter size, the evolution of body mass, or developmental landmarks. The offspring were tested as adults for learning deficits. EMF exposure was not associated with any measurable cognitive deficit.
Reference: Bornhausen M, Scheingraber H. Prenatal exposure to 900 MHz, cell-phone electromagnetic fields had no effect on operant-behavior performances of adult rats. Bioelectromagnetics 2000;21:566-574.
The authors of this study from Turkey exposed 12 pregnant rats to radiation in the range 890-915 MHz for 2 hours daily from the first day of pregnancy. The SAR was 0.155 W/kg. The exposed rats were compared to rats not exposed to radiation. Litter size was unaffected. Routine blood tests in the rats and in their offspring were normal. Birth weight of the irradiated rats, however, was lower than in the sham-exposed group. The weight deficiency was overcome by 3 months. The authors state that they do not know whether the birth weight decrease in the first generation offspring was a specific effect of microwave radiation or a nonspecific stress reaction. The rats were followed in their next pregnancy and the birth weight of offspring of this generation was normal.
Reference: Dasdag S, Akdag MZ, Ayyildiz O, Demirtas OC, et al. Do cellular phones alter blood parameters and birth weight of rats? Electro- and Magnetobiology 2000;19:107-113.
An article published recently in Radiation Research examined the effect of pulsed 2,450 MHz RF radiation on DNA in human lymphocytes. The blood cells were exposed for 2 hours to the radiation and the mean SAR was 2.135 W/kg. There was no evidence of any damage to the DNA either immediately or 4 hours after the radiation exposure. These results are in contrast to previous studies by Lai and Singh that reported DNA damage following RF radiation (see "Research - Toxicological - cancer studies"). The authors of the present study review possible reasons in the laboratory techniques for their failure to replicate the results of Lai and Singh.
Reference: Vijayalaxmi, Leal BZ, Szilagyi M, Prihoda TJ, et al. Primary DNA damage in human blood lymphocytes exposed in vitro to 2450 MHz radiofrequency radiation. Radiation Research 2000;153:479-486.